This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. There has been growing interest in the use of nano particles in the cell biology field as potential therapeutic and imaging agents. Nanometer sized particles have unique properties that allow them to be used in variety of applications, some of which are in vivo drug delivery, as well as imaging. One of the best studied nano particles in the last decades are the TiO2 nanoparticles. Because of the formation of the so called ''corner defects''on the surface of the TiO2 nanoparticle smaller than 20nm, this particles can be efficiently conjugated to DNA oligonucleotides. Peptide nucleic acid conjugated TiO2 nanoparticles that we are going to study, contain peptide backbones to which various nucleotides may be attached. The function of the peptides attached to TiO2 particles is to direct the particle uptake in the cell, where nucleic acids are important for the retention of this particles in particular subcellular compartment. In a recent paper by Wu et al., 2008, it was shown by AFM that nanoconjugates of TiO2 and DNA oligonucleotides can serve as anchors for binding of PCNA (proliferating cell nuclear antigen) protein trimers. It is completely unknown, what is the conformation of the nanoparticles, that will have peptide nucleic acid (PNA) attached to them, in solution. Because of the difficulty with which nanoparticles are characterized, and a general lack of techniques appropriate for such studies, SAXS SSAXS could prove to be an ideal technique for providing information concerning the location of the peptide nucleic acid on the TiO2 nano particles.